We have all heard of "double-blind" studies, but what does that mean? And are they always the essential standard of scientific data that we need to be confident that our information is accurate and helpful to our health?

A clinical trial is a prospective study in which the participants are placed into two groups based on a random division (to avoid bias in subject selection), and the subjects are not aware of which group they are in, the treatment or the control (a single-blind study). If the researchers also do not know which group is which before they break the code (they are coded for later evaluation) it is called a double-blind study. This is important because just knowing you are in treatment can influence the outcome – through the power of the mind to influence healing.

Even when the researchers know which group is which, they may pass subtle hints to the subjects, subconsciously or otherwise, that may influence the results. If the treatment is with medication, the control group is given an inactive pill called a placebo. Thus you will see references to "randomly-assigned, double-blind, placebo-controlled, clinical trials." (And some people refer to a triple-blind study where no one knows what is going on.)

Medical practitioners like to see "randomly assigned, double-blind, placebo-controlled, cross-over, clinical trials" in order to be sure that the results are meaningful, but the vast majority of medical practice as it is actually being done in the doctor’s office every day is not supported by such scientific data. This does not mean that the practice is wrong or bad, but only that medicine is an art as well as a science, and we can appreciate and benefit from the wisdom and understanding of the practitioner as well as the science of medicine.

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